Exploring the impact of fungus-algae microbial fertilizer on soil physical and chemical properties，bacterial communities，and functional genes involved in carbon，nitrogen，and phosphorus cycles in newly reclaimed farmland can provide a theoretical reference for ecological fertilization aimed at improving soil fertility and bacterial community activity in such farmland. The study selected newly reclaimed loess farmland for 2 years in the northwest arid area，setting up a control group( CK)and three groups treated with fungus-algae microbial fertilizer systems:single application of Pseudomonas aeruginosa( PSB)，single application of Chlorella pyrenoidosa( MF)，and mixed application of Pseudomonas aeruginosa and Chlorella pyrenoidosa( PM). Field experiments were conducted to explore the regulatory effects of fungusalgae microbial fertilizer on crop growth，soil fertility，bacterial diversity，and the activities of carbon，nitrogen，and phosphorus functional genes in newly reclaimed farmland. The results showed that:(1)The application of fungus-algae microbial fertilizer significantly increased sorghum yield，the PM treatment group had the highest ear weight and grain weight per ear，with the grain yield increasing to 5927 kg/hm²，which was 10.12% higher than the PSB treatment and 14.05% higher than the MF treatment；(2)Compared with the CK treatment，each treatment significantly increased the soil available potassium content by 13.54%-50.95%. The PM treatment group increased the contents of available phosphorus and ammonium nitrogen in the soil by 12.94% and 41.50%，respectively，while the soil organic carbon content decreased by 27.57%；(3)Drenching with fungus-algae microbial fertilizer improved the stability of soil bacterial communities in newly reclaimed farmland. Specifically，the PM treatment significantly increased the Alpha diversity of soil bacterial communities，enhanced the abundance of Actinomycetes，Proteobacteria，etc.，in the soil of newly reclaimed farmland，and significantly promoted the enrichment of beneficial bacterial genera such as Sphingomonas and Bacillus；(4)Compared with the CK treatment，the PM treatment enhanced soil carbon，nitrogen，and phosphorus cycling functions and significantly increased the total abundance of functional genes involved in these cycles. Therefore，the application of a mixed bacterial solution of Rhodopseudomonas palustris and Chlorella pyrenoidosa to newly reclaimed farmland improved soil bacterial diversity and carbon，nitrogen，and phosphorus metabolic activity，promoted the release of soil nutrients in newly reclaimed farmland，thereby enhancing soil biological fertility and promoting crop growth. The research results could provide a scientific basis for using fungus-algae microbial fertilizer to improve soil fertility in newly reclaimed farmland in arid areas.